L14 - Respiration 1

Question 1

What is external respiration?

Answer 1

ventilation or breathing i.e. exchange of air between atmosphere and lungs

Question 2

Which interactions occur in external respiration?

Answer 2

exchange of O2 and CO2 between lungs and blood
transport of O2 and CO2 by blood
exchange of O2 and CO2 between blood and cells

Question 3

What is internal or cellular respiration?

Answer 3

intracellular reaction of O2 with nutrients to produce CO2, water and energy

Question 4

What are other functions of the respiratory system?

Answer 4

1. aids in regulation of blood pH by altering amount of H+-generating CO2 exhaled
2. provides additional route for water loss and heat elimination
3. enhances venous return via “respiratory pump”
4. enables vocalisation and smell
5. defends against inhaled foreign matter

Question 5

What is the structure of the trachea and larger bronchi?

Answer 5

fairly rigid, non-muscular tubes

rings of cartilage prevent collapse

Question 6

What is the structure of bronchioles?

Answer 6

no cartilage to hold them open
walls contain smooth muscle innervated by autonomic nervous system
sensitive to certain hormones and local chemicals

Question 7

What is the structure of alveoli?

Answer 7

thin-walled sacs

site of gas exchange with capillaries

Question 8

What keeps the lung inflated?

Answer 8

1. pleural sac which attaches the lung to the thoracic wall

2. pressure difference between the atmosphere, lungs and pleural sac

Question 9

For the lung to remain inflated, pressure within the pleural sac must be _____ (greater than/less than/equal to) the pressure within the lung.

Answer 9

less than because if the pressure within the pleural sac was greater than the pressure in the lungs it would collapse in, therefore less than (lungs expand into the pleural space)

Question 10

What is intrapulmonary pressure?

Answer 10

the pressure within the alveoli - 760 mm Hg when equilibrated with atmospheric pressure

Question 11

What is intrathoracic pressure?

Answer 11

the pressure within the pleural sac - the pressure exerted outside the lungs within the thoracic cavity, usually less than atmospheric pressure at 756 mm Hg

Question 12

What causes pneuothorax?

Answer 12

atmospheric pressure in the pleural sac which results in collapse of the lungs because they are no longer able to expand into the pleural space due to lack of pressure gradient

Question 13

If there is air flow from A into B, then you know that the pressure in A is ______ (higher than/lower than/same as) the pressure in B.

Answer 13

higher than

Question 14

For air to move into lungs during inspiration, what must happen?

Answer 14

lung volume must increase, intra-alveolar pressure must decrease and intrapleural pressure must decrease

Question 15

For air to move out of the lungs during inspiration, what must happen?

Answer 15

lung volume must decrease, intra-alveolar pressure must increase and intrapleural pressure must increase

Question 16

How does expiration normally occur?

Answer 16

normally passive and occurs due to passive elastic recoil of lungs and thoracic cage

Question 17

When are muscles of expiration used?

Answer 17

only in forced breathing or voluntary exhalation

Question 18

Which muscles are used for breathing and how do they allow for breathing to occur?

Answer 18

external intercostal and scalene muscles contract to increase lung capacity and relax to decrease lung capacity

Question 19

What can ventilation be modulated by?

Answer 19

higher brain centres
medullary chemoreceptors
other chemoreceptors and mechanoreceptors